Particular difficulty has been found .Iadd.with various present brands of smoke spot testers and their use thereof .Iaddend.in the present method of spot testing the smoke content in the flu pipe of an oil burner. Namely, that the filter paper in common use today is in strip form .[.and.]..Iadd.. The strip is .Iaddend.obtained by the technician tearing off a useable piece of paper from a serrated sheet to form a useable strip. Herein lies one of the difficulties. Usually the technician making the test has either serviced the oil burner or had made an inspection. As a result has hands are quite often covered by a quantity of soot, oil dust, and etc,. inherent with and generally found around an oil burner. Hence, the moment he selects a filter strip he imparts a print or smudge from his hands onto the filter paper even before he makes a test. This contamination can degrade the test data and lead to erroneous conclusions. Also, the concept of placing a small strip of limp paper in a narrow slot is awkward, and difficult and often falls out and onto the floor where it is further dirtied.
Another difficulty of importance is that after a spot test has been made, the test strip of filter paper must be moved or removed from the spot tested for inspection. In so doing, the test paper can be easily dropped, further contaminating the test or becoming disorientated. Since several tests are usually made on one strip a disorientation of the test strip can be confused with the first test or any other test, depending on how the paper was moved after each test.